Process of treating coal and product



Patented Jan. 22, 1935 I Noel Cunningham, Bethlehem, Pa., and Charles Lee Peck, Mount Vernon, N. Y., asaignors to The Champion Fibre Company, a corporation No Drawing. Application December 28, 1932, Serial No. 649,232

8Claims.

The present invention relates to the treatment of coal with an aqueous composition adapted to render the same dustless, to the treating composition, and to the coal product resulting from such treatment. More particularly, the invention is concerned with the provision of a method for permanently laying the dust of dusty coals.

It heretofore has been proposed to treat coal, e. g., dusty bituminous coal, with aqueous dustlaying compositions of various sorts. These previously-used compositions may, for convenience, be grouped into three classes, depending upon their effect, as follows:

.1. Compositions which bind the dust to the ample: neutralized waste sulphite liquor) 2. Compositions which lay the dust by virtue of an agglomerating effect (example: aqueous emulsion of petroleum oils);

3. Compositions which lay the dust by virtue of the hygroscopicity of a constituent or constituents thereof (example: aqueous solution of hygroscopic salts such, for instance, as calcium chloride).

A difliculty common to known compositions of all three of the above classes obtains in attempting to lay the dust of bituminous coals,

viz., that the compositions are incapable of wetting the coal and/ or of penetrating the same, the coal being of an oily mixture repellent to water, i with the result that the composition is distributed over the coal with difficulty, becomes irregularly distributed over the coal, lies thereon in unabsorbed globules, etc. Thus, it had been found necessary to distribute the hitherto-proposed compositions in atomized condition, and to use a large excess of composition, in order to obtain a useful efiect. Furthermore, the use of hygroscopic salts has proved to be attended by 40 disadvantages including: damage to the boiler; an objectionable appearance to the treated coal, etc. In the case of many of these hitherto-proposed compositions, it is necessary to employ such large amounts of water, per ton of coal (e. g., 2 or 3% or more of the amount of the coal) as to prohibit the practical application of these compositions by reason of the increase in weight and of the decrease in fuel value of the resulting product. Also the successful atomization of such compositions requires relatively expensive equipment and supervision, and is attended by annoyance and harm to the operatives.

An obj ectof the present invention is the provision of a coal dust-laying composition capable of wetting and/or penetrating the cook-particucoal by a "gluing or varnishing function (exlarly dusty bituminous coal. Another object of invention 'is the provisior of a dust-laying composition capable of permanently laying coal dust when used in relatively small amounts. Still another object is the provision of a coal dust-laying composition which may be applied to coal by an ordinary sprinkling process.

The above, and other objects of invention, are attained by distributing over the coal an aqueous composition consisting essentially of, or containing, a material which is separated from the black liquor of sulphate or soda pulp mills operating upon resinous woods. It has been found that aqueous dust-laying compositions containing a relatively small amount of this separated material (hereinafter more fully described) wet and/or penetrate coal, e. g., dusty bituminous coal, and that treatment of coal with a dustlaying composition containing this mate and a compatible dust-layer makes the coal uniform- 2 ly and permanently dustless. It has been found, further, that the appearance and other physical characteristics of soft coals, particularly of bituminous slack, are improved by the aforesaid treatment, whereby the coal is made more valuable. Thus, the treatment not only permanently lays the dust of bituminous'slack' but also makes the coal brighter, more nearly black, and more readily handled.

If the so'treated coal, after complete drying, is

subsequently treated with water, it quickly absorbs the water. This phenomenon may be taken advantage .of by treating coal with a solution of the aforesaid black liquor by-product, and, at a subsequent time, treating the product with water.

The black liquor by-product whose wetting and/or penetrating property toward coal is the basis of the present invention is a pasty material, of the consistency of butter and of a brown to black color, which separates, either as a surface scum or as a precipitate according to the salt concentration of the black liquor, from alkaline black liquor either upon standing and cooling or upon reducing the water content (and correspondingly increasing the salts contents) thereof. 45

In the form in which it is separated from black liquor it contains upwards of 30 of water; when completely dehydrated it is a very hygroscopic solid having a resinous appearance (i. e., a solid having a resinous fracture, brittle when cold but becoming gummy at about 0.). This byproduct, as such or in anhydrous form, is soluble in water giving a relatively clear solution containing colloidal lignin and soluble fatty and resinous substancesi The latter are believed to be u 2 v degradation products of resins; or degraded resins, distinguishable from naturalrosin; the relative content of degraded resin to fatty substances is about as 2 into 1. The material hydrolyzes in water to a solutiton alkaline to phenolphthalein. It contains about 6 .to 8% of unsaponiflable organic matter, chiefly lignous material derived from wood by the alkaline digestion process. when this material (that is, the agent separated from alkaline black liquor) is treated with a strong acid, e. g., strong mineral acid, there is set free a soft, permanently tacky or sticky substance. This semi-solid soapy material has been described in Patent No. 1,823,752 to Michelson as being a soap" found floating on the alkaline waste liquor recovered in the manufacture of sulphate or sodium cellulose, the soap" consisting substantially of alkali salts of fatty or resinous acids. In Chemistry of Pulp and Paper Making", Sutermeister, 2nd ed., 1929, at pages 171-172 are given analyses of alkaline black liquor from the sulphate and soda pulping processes, wherein the analysis by Klason and Segerfeld shows the presence, in such liquors, of about 2.5% fatty and resinous acids. Preparation of a soap" from the supernatant soapy material found floating on alkaline waste liquors is described at page 120 of The Manufacture of Pulp and Paper, Vol. III, published by McGraw-Hill. The amount of lignous material contained in this soapy material depends upon the degree of washing of the "cream" coming from the black liquor.

It has been found that an aqueous emulsion of oil, e. g., fuel oil distillate or the like, and the aforesaid alkaline black liquor by-product does not require atomization in order to be distributed evenly over coal, but may be distributed simply by sprinkling the aqueous liquid over the coal from an ordinary water sprinkler mhv way of a hose equipped with an ordinary water-sprinkling nozzle. The economy effected by the use of this compostion may be illustrated by stating that it requires only about two gallons of such composition, per ton of low-grade bituminous slack, to effect the same dust-laying effect as is obtained by treating identical coal, at the rate of 16 gallons per ton, with a composition consisting of 6 parts by volume of so-called miscible oil emulsified in 94 parts by volume of water. Coal treated in the manner described and claimed herein has just as great B. t. u. value as, and in known cases even greater B. t. u. value than, the same coal in an untreated state: the treatment does not diminish the fuel value, or impede the combustion, of coal.

The invention will be described in greater detail by reference to the following illustrative examples:

Example I An emulsion was prepared from water, fuel oil distillate and the aforesaid alkaline black liquor by-product, in the following proportions:

.Black liquor by-product 50 lbs. Water 55 gals. Fuel oil distillate 60 gals.

with the foregoing composition by sprinkling the latter over the former the amounts of composition used in each case to permanently lay. the dust of 1 ton of coal being as follows:

2 gallons of composition, on "New river bituminous slack; gallon of composition, on Imperial" bituminous nut; V gallon of composition, on anthracite nut. i I

It will be noted that, using "New river" slack as the illustration, the composition should be used in an amount to provide 1 gallon of oil per ton of coal regardlessof the extent of dilution and of the proportion of black liquor by-product.

In comparing the results obtained by the use of the foregoing composition with those obtained by the use of an aqueous emulsion of fuel oil, it was found that about 10 times as much was required to obtain the same dust-laying eil'ect in the latter instance as in the former. In connection with this comparison it was observed that while the coal treated with emulsified oil was 'dustless it was an objectionable product in that it contained more water than is customarily thought permissible in a solid fuel, was sensibly wet, and was a diillcultly-marketable coal.

It is believed that the lower limit of content of the aforesaid alkaline black liquor by-product in the water-oil composition necessary to obtain desired penetration and/or wetting of coal is represented in the following formula:

' Percent Alkaline black liquor by-product 4.7 Water 38.! Fuel oil distillate 56.6

An increase in content of said black liquor byproduct gives rise to a corresponding increase in rate of penetration of the composition.

It has been found, also, that treatment of anthracite coal with an aqueous solution of the aforesaid alkaline black liquor by-product is effective in making the coal permanently dustless. Thus, one pound of the said by-product dissolved in one gallon of water and distributed over one ton of anthracite nut coal made the latter permanently dustless. It may be remarked that in the case of treatment of anthracite coal which has been washed with acidic mine water, there may be in the coal a sufllcient acid content to react with the by-product setting free the soft, sticky, substance (apparently degraded resin) hereinbefore referred to.

As will be obvious, the black liquor by-product may be added to the other constituent or constituents of the coal-treating composition either in paste form (containing upwards of 30% water) or in anhydrous form. If desired, one may preliminarily treat the said by-product with mineral acid, releasing a solid substance insoluble in water, which insoluble solid may thereafter be treated with an appropriate amount of a suitable alkali to restore its solubility before use.

By the expression alkaline black liquor byproduct used in the appended claims is meant the hereinbefore-described semi-solid (either as such or in anhydrous form) which separates from the alkaline black liquor, of sulphate or soda pulp mills, upon cooling or upon concentrating the solids content thereof, said "alkaline black liquor by-product being the so-called soap floating on the waste-liquors obtained in the manufacture of sulphateor sodium cellulose. The said expression is intended to exclude lignin liquors as such and also lignosulphonic acids and relates specifically to the material described as a starting material in U. to Michelson.

We claim:

1. Process of rendering a solid carbonaceous fuel permanently dustless, which comprises distributing thereover a relatively small amount of an aqueous composition containing as an active ingredient alkaline black liquor by-product.

2. Process of rendering a solid carbonaceous fuel permanently dustless, which comprises distributing thereover a relatively small amount of an aqueous composition containing petroleum oil and alkaline black liquor by-product.

3. In the process of rendering coal permanently dustless by the distribution thereover of an aqueous dust-laying composition containing a material amount of petroleum oil, the improvement which consists in combining with the other ingredients in said composition a relatively small s. Patent No. 1,823,752

but efiective amount of alkaline black liquor by-product".

4. Process of rendering bituminous coal permanently dustless, which comprises distributing thereover, in the proportion of from about twothirds of a gallon to about two gallons per ton of coal, a liquid composition consisting essentially of petroleum oil, water and alkaline black liquor by-product in about the ratio of 50 pounds of carbonaceous fuel to make the latter.permanent-- ly dustless, said emulsion containing a minor but eifective amount of alkaline black liquor byproduct as a penetrant.

'7. A petroleum oil-water emulsion for treating a solid carbonaceous fuel to make the latter permanently dustless, said emulsion containing a minor but eifective amount of alkaline black liquor by-product" as a penetrant.

8. An oil-water emulsion for treating a solid carbonaceous fuel to make the latter permanently dustless, said emulsion consisting essentially of "alkaline black liquor by-product, water and fuel oil distillate in about the following proportions:

Alkaline black liquor by-product 5 0 lbs. Water 55 gals. Fuel oil distillate 60 gals.

NOEL CUNNINGHAM. CHARLES LEE PECK. 

